Protective effect of melatonin against gentamicin ototoxicity.
OBJECTIVE
To research the protective effect of melatonin against gentamicin ototoxicity.


METHODS
Guinea pigs were randomly divided into four groups. The first group received intramuscular gentamicin (120 mg/kg body weight/day) for 17 days. Over the same time period, a second group simultaneously received intramuscular gentamicin (120 mg/kg body weight/day) plus (on the other side) intramuscular melatonin (0.3 ml kg body weight/day). Two groups of controls were treated for 17 days with either intramuscular melatonin or intramuscular saline. After the 17 days, each animal underwent distortion product otoacoustic emission testing (both ears). The guinea pigs were sacrificed by decapitation just after the final injection. Their cochleae were used to produce a tissue section, surface preparation and scanning electron microscope preparation.


RESULTS
Distortion product otoacoustic emission testing indicated gentamicin-induced hearing loss at 3, 4, 6 and 8 kHz in gentamicin-treated animals. Animals receiving melatonin co-therapy had significantly attenuated hearing loss and their cochleae showed lower rates of outer hair cell loss (comparing the same cochlear turns), compared with gentamicin-treated animals (p < 0.01).


CONCLUSIONS
These findings confirm the occurrence of outer hair cell loss after gentamicin treatment, and the attenuation of such loss following simultaneous melatonin injection, using the method of morphological evaluation. These results suggest that melatonin protects against gentamicin ototoxicity by interfering with cytotoxic mechanisms.
Ye
L-F
LF
Department of Otolaryngology, Zhongnan Hospital of Wuhan University, Hubei, People's Republic of China.
Tao
Z-Z
ZZ
Hua
Q-Q
QQ
Xiao
B-K
BK
Zhou
X-H
XH
Li
J
J
Yuan
Y-L
YL
D000818:Animals; D000900:Anti-Bacterial Agents / Q000633:toxicity*; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology; D004347:Drug Interactions; D005839:Gentamicins / Q000633:toxicity*; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects; D034381:Hearing Loss / Q000139:chemically induced / Q000517:prevention & control*; D008550:Melatonin / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects; D011897:Random Allocation; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008550:Melatonin